const hexcase = 0 /* hex output format. 0 - lowercase; 1 - uppercase        */
const b64pad = '' /* base-64 pad character. "=" for strict RFC compliance   */
const chrsz = 8 /* bits per input character. 8 - ASCII; 16 - Unicode      */

/*
 * These are the functions you'll usually want to call
 * They take string arguments and return either hex or base-64 encoded strings
 */
export function hex_sha1(s: string): string {
  return binb2hex(core_sha1(str2binb(s), s.length * chrsz))
}
function b64_sha1(s: string): string {
  return binb2b64(core_sha1(str2binb(s), s.length * chrsz))
}
function str_sha1(s: string): string {
  return binb2str(core_sha1(str2binb(s), s.length * chrsz))
}
function hex_hmac_sha1(key: string, data: string): string {
  return binb2hex(core_hmac_sha1(key, data))
}
function b64_hmac_sha1(key: string, data: string): string {
  return binb2b64(core_hmac_sha1(key, data))
}
function str_hmac_sha1(key: string, data: string): string {
  return binb2str(core_hmac_sha1(key, data))
}

/*
 * Perform a simple self-test to see if the VM is working
 */
function sha1_vm_test(): boolean {
  return hex_sha1('abc') == 'a9993e364706816aba3e25717850c26c9cd0d89d'
}

/*
 * Calculate the SHA-1 of an array of big-endian words, and a bit length
 */
function core_sha1(x: number[], len: number): number[] {
  /* append padding */
  x[len >> 5] |= 0x80 << (24 - (len % 32))
  x[(((len + 64) >> 9) << 4) + 15] = len

  const w = Array(80)
  let a = 1732584193
  let b = -271733879
  let c = -1732584194
  let d = 271733878
  let e = -1009589776

  for (let i = 0; i < x.length; i += 16) {
    const olda = a
    const oldb = b
    const oldc = c
    const oldd = d
    const olde = e

    for (let j = 0; j < 80; j++) {
      if (j < 16) w[j] = x[i + j]
      else w[j] = rol(w[j - 3] ^ w[j - 8] ^ w[j - 14] ^ w[j - 16], 1)
      const t = safe_add(
        safe_add(rol(a, 5), sha1_ft(j, b, c, d)),
        safe_add(safe_add(e, w[j]), sha1_kt(j))
      )
      e = d
      d = c
      c = rol(b, 30)
      b = a
      a = t
    }

    a = safe_add(a, olda)
    b = safe_add(b, oldb)
    c = safe_add(c, oldc)
    d = safe_add(d, oldd)
    e = safe_add(e, olde)
  }
  return [a, b, c, d, e]
}

/*
 * Perform the appropriate triplet combination function for the current
 * iteration
 */
function sha1_ft(t: number, b: number, c: number, d: number): number {
  if (t < 20) return (b & c) | (~b & d)
  if (t < 40) return b ^ c ^ d
  if (t < 60) return (b & c) | (b & d) | (c & d)
  return b ^ c ^ d
}

/*
 * Determine the appropriate additive constant for the current iteration
 */
function sha1_kt(t: number): number {
  return t < 20
    ? 1518500249
    : t < 40
    ? 1859775393
    : t < 60
    ? -1894007588
    : -899497514
}

/*
 * Calculate the HMAC-SHA1 of a key and some data
 */
function core_hmac_sha1(key: string, data: string): number[] {
  let bkey = str2binb(key)
  if (bkey.length > 16) bkey = core_sha1(bkey, key.length * chrsz)

  const ipad = Array(16),
    opad = Array(16)
  for (let i = 0; i < 16; i++) {
    ipad[i] = bkey[i] ^ 0x36363636
    opad[i] = bkey[i] ^ 0x5c5c5c5c
  }

  const hash = core_sha1(ipad.concat(str2binb(data)), 512 + data.length * chrsz)
  return core_sha1(opad.concat(hash), 512 + 160)
}

/*
 * Add integers, wrapping at 2^32. This uses 16-bit operations internally
 * to work around bugs in some JS interpreters.
 */
function safe_add(x: number, y: number): number {
  const lsw = (x & 0xffff) + (y & 0xffff)
  const msw = (x >> 16) + (y >> 16) + (lsw >> 16)
  return (msw << 16) | (lsw & 0xffff)
}

/*
 * Bitwise rotate a 32-bit number to the left.
 */
function rol(num: number, cnt: number): number {
  return (num << cnt) | (num >>> (32 - cnt))
}

/*
 * Convert an 8-bit or 16-bit string to an array of big-endian words
 * In 8-bit function, characters >255 have their hi-byte silently ignored.
 */
function str2binb(str: string): number[] {
  const bin: any[] = []
  const mask = (1 << chrsz) - 1
  for (let i = 0; i < str.length * chrsz; i += chrsz)
    bin[i >> 5] |= (str.charCodeAt(i / chrsz) & mask) << (32 - chrsz - (i % 32))
  return bin
}

/*
 * Convert an array of big-endian words to a string
 */
function binb2str(bin: number[]): string {
  let str = ''
  const mask = (1 << chrsz) - 1
  for (let i = 0; i < bin.length * 32; i += chrsz)
    str += String.fromCharCode((bin[i >> 5] >>> (32 - chrsz - (i % 32))) & mask)
  return str
}

/*
 * Convert an array of big-endian words to a hex string.
 */
function binb2hex(binarray: number[]): string {
  const hex_tab = hexcase ? '0123456789ABCDEF' : '0123456789abcdef'
  let str = ''
  for (let i = 0; i < binarray.length * 4; i++) {
    str +=
      hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8 + 4)) & 0xf) +
      hex_tab.charAt((binarray[i >> 2] >> ((3 - (i % 4)) * 8)) & 0xf)
  }
  return str
}

/*
 * Convert an array of big-endian words to a base-64 string
 */
function binb2b64(binarray: number[]): string {
  const tab = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
  let str = ''
  for (let i = 0; i < binarray.length * 4; i += 3) {
    const triplet =
      (((binarray[i >> 2] >> (8 * (3 - (i % 4)))) & 0xff) << 16) |
      (((binarray[(i + 1) >> 2] >> (8 * (3 - ((i + 1) % 4)))) & 0xff) << 8) |
      ((binarray[(i + 2) >> 2] >> (8 * (3 - ((i + 2) % 4)))) & 0xff)
    for (let j = 0; j < 4; j++) {
      if (i * 8 + j * 6 > binarray.length * 32) str += b64pad
      else str += tab.charAt((triplet >> (6 * (3 - j))) & 0x3f)
    }
  }
  return str
}
